I may be wrong, but I believe a there are a few NDP EMS ambulances out there that at CT plates but also NYS DOH certified. Also, I can speak for the HVP/REMS "thing", the REMS trucks had NY plates, but were also DOH certified in PA.
EMS company I used to be with changed the colors and the region said nothing about it. After all, there are more than one NYS EMT/Medic style of patches out there.